1. Field of the Invention
The present invention relates to a device and a link control method for inter-chip connection, especially to an SSIC (SuperSpeed Inter-Chip) device and an SSIC device link control method.
2. Description of Related Art
SSIC (SuperSpeed Inter-Chip) technique is open standard technique developed by USB-IF (USB Implementers Forum), characterized by low power consumption and high transmission speed.
A general SSIC device is capable of connecting with an SSIC host under the following four modes:    U0 mode: a full-speed operation mode, allowing the SSIC device to carry out full-speed transmission and reception immediately and therefore consuming the most power among the four modes;    U1 mode: a fast-recovery mode, allowing the SSIC device to reduce power consumption and return to U0 mode quickly;    U2 mode: a slow-recovery mode, allowing the SSIC device to reduce more power consumption and return to U0 mode slowly in comparison with U1 mode; and    U3 mode: a sleeping-mode, allowing the SSIC device to achieve the lowest power consumption among the four modes.
In light of the above, although U3 mode consumes the lowest power among the four modes, a general SSIC device is unable to enter U3 mode actively. It is an SSIC host that decided the SSIC device to enter U3 mode. Therefore, even though the SSIC device (e.g., an SSIC card reader) does not connect with an external object (e.g., an SSIC compatible memory card) or the external object cannot be identified or read, the SSIC device is still unable to actively enter U3 mode, or actively stop the transmission/reception function between the SSIC host and it for the reduction in power consumption. It should be noted that the aforementioned SSIC device and the SSIC host could be two parts (e.g., two integrated chips) of an electronic device (e.g., a personal computer, or a mobile device), and could be installed on a circuit board of the electronic device and connected with each other through the wiring of the circuit board or installed on two circuit boards respectively and connected with each other through a connection interface between the two circuit boards. Furthermore, the SSIC device and the SSIC host could be two parts capable of being connected with or independent of each other with an appropriate interface.
People who are interested in the detail of an SSIC device and an SSIC host can refer to the following specification: “Inter-Chip Supplement to the USB Revision 3.0 Specification”, Revision 1.01, Feb. 11, 2013”.